Hi, I have a doubt about using of projections in OrientDB.
My case is the following: suppose we have to classes named respectively demo and drug. First class contains patient demographic and administrative information and the second one contains drug and biologic information. Classe demo and drug have a 1-to-many relationship, in fact for every one item in demo class, we can have one or more records in drug class. Well, suppose event_dt is an attribute of demo class and drugname is an attribute of drug class: in a relational database (for instance MySQL) I can define a query as follow (suppose primaryid is a common attribute used as foreign key): select demo.event_dt, drug.drugname from demo, drug where demo.primaryid = drug.primaryid; In OrientDB I created a class namerd drugToDemo as edge that have the scope to link demo and drug class records. According to tutorial[0], because the relationship is 1-to-many I can do the following query: select out_drugToDemo.event_dt, drugname from drug limit 5 and this result: +----+--------------+---------+ |# |out_drugToDemo|drugname | +----+--------------+---------+ |0 |[20000118] |AVONEX | |1 |[20000118] |AVONEX | |2 |[20000118] |ZOLOFT | |3 |[20000118] |LIPITOR | |4 |[20000118] |SYNTHROID| +----+--------------+---------+ I think the first column obtained is populated by arrays of single elements, right? In fact if I do the following query: select out_drugToDemo.event_dt[0] as event_dt, drugname from drug I obtained this result, similar to result that I can obtain in MySQL: +----+--------+---------+ |# |event_dt|drugname | +----+--------+---------+ |0 |20000118|AVONEX | |1 |20000118|AVONEX | |2 |20000118|ZOLOFT | |3 |20000118|LIPITOR | |4 |20000118|SYNTHROID| +----+--------+---------+ I can do this query because I'm sure that for every record of drug class I can have exactly on record of demo class. Now, for instance I try to do the following query: select event_dt, in_drugToDemo.drugname from demo Because I can have for every item in demo class, none, one, or more record of drug class I obtained a result similar to the following: +----+--------+----------------------------------+ |# |event_dt|in_drugToDemo | +----+--------+----------------------------------+ |0 |20000118|[AVONEX,ZOLOFT,LIPITOR,SYNTHROID] | |1 |20021015|[AVONEX,ACETAMINOPHEN.] | |2 |20040204|[GLIVEC,CYLOCIDE,LASIX,FOY] | |3 |200011 |[TACROLIMUS.,AZATHIOPRINE.] | |4 |200303 |[AVONEX,RITALIN,WELLBUTRIN,RXANAX]| +----+--------+----------------------------------+ Now, my question is: how I can expand arrays obtained by navigating into in-edge drugToDemo and list all results as single items? For instance, if I try the following: select event_dt, expand(in_drugToDemo.drugname) from demo; I obtain the following result: +----+----------+ |# |value | +----+----------+ |0 |AVONEX | |1 |ZOLOFT | |2 |LIPITOR | |3 |SYNTHROID | |4 |AVONEX | +----+----------+ but event_dt is now showed as result. Another question: if I want to project all attributes of classes what do I do? In other words, how I can do a query as following in OrientDB? select demo.*, drug.* from demo, drug where demo.primaryid = drug.primaryid Thanks for patience, I hope I was clearly in explaination of my issue. Kind regards. [0] http://orientdb.com/docs/last/Tutorial-Relationships.html -- Fabio Rinnone Skype: fabiorinnone Web: http://www.fabiorinnone.eu -- --- You received this message because you are subscribed to the Google Groups "OrientDB" group. To unsubscribe from this group and stop receiving emails from it, send an email to orient-database+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
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